1. Field of the Invention
This invention relates to a secondary system for operating a vehicle air conditioning unit and other accessories. The invention is particularly intended for tractor-trailers for long-distance trucking, but could be adapted to other vehicle types as desired.
Although vehicle air conditioning and accessories can be operated by running the primary engine of the vehicle, this is very wasteful in terms of energy consumption, even at lower running speeds, and generates excessive exhaust emissions. There is a need for a system which allows the air conditioner and other accessories to be operated without running the primary engine, and without excessive energy consumption and emissions.
2. Description of the Prior Art
U.S. Pat. No. 3,844,130 (Wahnish) describes a system which superficially is somewhat similar to that of the present invention, but which involves a significantly more complicated clutching arrangement, among other disadvantages. In Wahnish, there are two pulleys on the end of the air conditioning compressor shaft which cannot rotate independently. Therefore three clutches are required for the system to be operable, namely one at the fan (primary engine) location, one at the compressor location, and one at the electric (auxiliary) motor location. For the primary vehicle engine to drive the compressor in normal vehicle operation, the fan clutch and the compressor clutch must be engaged, and the electric motor clutch must be disengaged. For the electric motor to drive the compressor, i.e. when the primary vehicle engine is not operating, the fan clutch needs to be disengaged, and the compressor clutch and electric motor clutch need to be engaged.
U.S. Pat. No. 4,531,379 (Diefenthaler, Jr.) describes a system which is also superficially somewhat similar to that of the present invention, but which uses a mechanical connection, via a xe2x80x9cjack shaftxe2x80x9d assembly, between an auxiliary engine and the air conditioner compressor, among other significant differences. It is quite a complex system, and in most vehicles, even large trucks, would be quite impractical in terms of space demands. The auxiliary engine and jack shaft assembly must be physically accommodated adjacent the air conditioner compressor, which is plainly impossible in many vehicles, or impractical in almost all. Diefenthaler, Jr. also fails to provide for independent operation of the air conditioning system, since there is a dual pulley which simultaneously drives the air conditioner compressor and the water pump which cools his auxiliary engine.
In view of the above, it is an object of the invention to provide a secondary system for operating the vehicle air conditioner and other accessories, and for battery charging, which is simple, inexpensive and easy to install, in an area of limited space, and which avoids the complexity and other problems of the above-mentioned prior art.
In the invention, an auxiliary power source such as a small gas or diesel engine is used to generate electricity through an alternator, which is used to charge the vehicle battery and selectively run an electric motor. The electric motor is connected via a centrifugal clutch, and a drive belt on a pulley integral to the clutch, to a pulley mounted to the drive shaft of the vehicle""s air conditioner compressor. The electricity can also be used to operate other accessories, if desired, such as lighting, televisions, VCRs, refrigerators and other like accessories.
In the invention, the pulley at the air conditioner compressor location which carries the belt from the electric motor can rotate independently of the pulley which carries the belt to the primary engine. This is because it is bolted directly to the end of the compressor drive shaft, not to the other (clutched) pulley. Operation of the system therefore does not require a clutch at the primary engine location; the electric motor can therefore drive the compressor with the belt to the primary engine, (and its pulley at the compressor location) remaining stationary. Nor does the invention make any use of the vehicle""s electromagnetic clutch at the compressor location.
Installation of the system is therefore much simpler than with any of the prior art systems; the auxiliary motor is installed at any suitable location, the additional pulley is bolted to the front of the compressor drive shaft, the electric motor with its centrifugal clutch is mounted nearby, a belt is installed between the additional pulley and the pulley which is integral with the centrifugal clutch, and the appropriate wiring connections are made as will be described in detail later. Thus a vehicle can be retrofitted with this system quickly and inexpensively.
Further features will be described or will become apparent in the course of the detailed description which follows.